Activities of the principal brain vesicular monamine transporter, VMAT2, are key to understanding the cellular compartmentalization of monoamines that may play a key role in modulating the actions and neurotoxicities induced by amphetamine and related psychostimulants. In previous FYs, investigators in this Branch identified cDNAs encoding human VMAT2, identified patterns of cellular VMAT2 expression in the brain, and identified polymorphisms at the human VMAT2 gene locus. To extend understanding of ways in which VMAT2 is expressed and ways in which gene variants might alter the rewarding and/or neurotoxic properties of amphetamines, these investigators have worked during this FY to complete cloning of murine VMAT2 cDNA and genomic DNA clones from ES cell lines and to define the VMAT2 genomic structure and major transcriptional start sites for the VMAT2 gene. Sequence analysis of 5' flanking sequences revealed a putative promoter region containing several consensus sequences for transcription factor binding. Analyses of these cDNA and genomic clones allows construction of targeting vectors for deletion of several VMAT2 exons in homologous recombinant "knockout" mice, and overexpression constructions for standard transgenic mice.